[CAUT] inharmonicity in piano wire

[Fred Sturm]

On Feb 5, 2009, at 9:57 AM, Cy Shuster wrote:

> Dr. Sanderson told me it's because higher frequencies propagate  
> through wire faster, and thus resolve as sharper than the  
> fundamental (which I don't completely understand).  It's *not*  
> because of dead space occupied by the nodes between individual  
> waves, he said.

	I won't claim to understand completely, but the propagation  
phenomenon can be grasped better on an intuitive level by looking at  
the high speed videography samples Birkett has posted on his website.  
I find the bass strings and the Wapin ones most useful. The bass  
strings clearly show the deformation caused by the hammer blow  
traveling (being propagated) to the bridge, then being reflected back  
in reverse (down instead of up). There is also a kind of "shivering"  
effect, where you can see a faster component as well as the slower,  
larger one. In the Wapin film, focused on the bridge pin, you see a  
periodic larger vibration, accompanied by a "shivering" effect, which  
is, presumably, the higher partials activating the bridge pin.
	It's a very complex thing going on, and hard to get all the details  
to fit together.
Regards,
Fred Sturm
University of New Mexico
fssturm at unm.edu